Source / Purification

Polyclonal antibodies are produced by immunizing animals with a synthetic peptide corresponding to residues surrounding Thr163 of human PAR-4 (Thr155 in rat and Thr156 in mouse). Antibodies were purified by protein A and peptide affinity chromatography.

Background

PAR-4 (prostate apoptosis response-4) was identified as a protein that is upregulated in prostate tumor cells undergoing apoptosis (1). Additionally, in parallel studies PAR-4 was found in the yeast two-hybrid system to bind to the Wilms' tumor suppressor protein WT1 and may modulate WT1-medated transcriptional activation (2). PAR-4 contains a leucine zipper domain and a death domain and has been implicated as an effector of apoptosis during tumorigenesis as well as in neurodegenerative disorders (3,4). PAR-4 is widely expressed in normal tissues but can be downregulated in some tumor types. The mechanism of PAR-4 mediated apoptosis regulation appears to be complex and dependent on the cellular context. Studies have indicated roles for PAR-4 in activation of the Fas-FADD-caspase-8 pathway as well as inhibition of the NF-κB pro-survival pathway (5-7). Its activity is likely to depend on the cellular context and post-translational modifications. For instance, phosphorylation of PAR-4 by Akt prevents its nuclear translocation thereby promoting cell surivival (8). In contrast, phoshorylation of rat PAR-4 at T155 by PKA appears to positively regulate its apoptotic activity (9).